Hepatocellular carcinoma (HCC), the fifth most common cancer and the second most common cause of cancer-related deaths worldwide, has no effective treatment for advanced disease. The present proposal focuses on two interacting oncogenes, AEG-1 and MDA-9, promoting HCC development and progression. Our studies over the last decade has firmly established that AEG-1 functions as a bona fide oncogene for HCC and we have developed the methodology of targeted nanoplexes delivering AEG-1 siRNA (PAMAM- AEG-1si) that markedly inhibits orthotopic human HCC xenografts in nude mice. We now document that MDA-9 is overexpressed in human HCC patients and MDA-9 plays an important role in regulating invasion and angiogenesis induced by HCC cells. TCGA database analysis reveals that AEG-1 and MDA-9 genes are co-amplified in human HCC patients. We identify a novel interaction between AEG-1 and MDA-9 in cell membrane of human HCC cells and demonstrate that they cooperate to promote HCC. We have now developed a novel, specific small molecule inhibitor of MDA-9 (PDZ1i), displaying excellent PK and ADME properties, which significantly reduces invasion by human HCC cells, and markedly inhibits human HCC xenografts in combination with sorafenib, an FDA-approved drug for unresectable HCC. PDZ1i also shows added inhibitory effect on the growth of xenografts of human HCC cells in which AEG-1 has been knocked out. The long-term objective of the present proposal is to develop effective targeted therapies for HCC that will provide significant survival benefit to HCC patients. Our immediate objective is to stringently evaluate PDZ1i and PAMAM-AEG-1si, and PDZ1i and sorafenib combinatorial therapies in immunocompetent mouse models of HCC, and decipher the molecular mechanism(s) by which AEG-1 and MDA-9 cooperate to promote HCC. All these components are innovative and have high mechanistic and translational significance. Sorafenib is routinely used for HCC treatment and combination of sorafenib and PDZ1i, if proven successful in our proposed animal models, has the potential to be fast-tracked for evaluation in Phase I/II clinical trials. For AEG-1 siRNA we have specifically chosen a nanoparticle delivery system which is already FDA approved, and note that RNAi therapy is showing promise in current HCC clinical trials, in the expectation of effective and rapid translation of results of PDZ1i and PAMAM-AEG-1si combinatorial therapy to practice. Successful completion of our research holds promise for establishing an effective therapeutic protocol for advanced HCC that will help significantly prolong the lives of scores of HCC patients.